3D printed GelMA/HAMA based mechanical microenvironment boosted PDAC chemoresistance via NRF2-repressed ferroptosis.

As a highly aggressive solid tumor, pancreatic ductal adenocarcinoma (PDAC) is featured by a conspicuous tumor microenvironment (TME) with abundant extracellular matrix (ECM) deposition, such as collagen and hyaluronic acid (HA). Accompanying with the pathological process, the dense matrix caused stiffen microenvironment, which leads to poor chemotherapy. Therefore, understanding the potential mechanism of mechanical microenvironment on PDAC chemoresistance is of great significance. To this end, 3D printed methacrylated gelatin (GelMA) and hyaluronic acid methacryloyly (HAMA) hydrogel model was fabricated to resemble the mechanical microenvironment of PDAC. The results presented that the PDAC cell lines (MIA-PaCa2 and PANC-1) embedded in the hydrogel were distinctively less sensitive to gemcitabine compared to tissue culture plate (TCP) group. Interestingly, immunofluorescence staining and qRT-PCR assay demonstrated that the NRF2 level was elevated, which further upregulated the downstream effectors, such as SLC7A11 and GPX4. Meanwhile, the GSH concentration and GPX4 activity of hydrogel group were increased, while the lipid peroxidation level was reduced, which indicated that the matrix stiffness microenvironment mediated ferroptosis phenotype. Furthermore, RNA interference experiment elaborated that shNRF2 group showcased significantly enhanced sensitivity to gemcitabine, which demonstrated that the biomimetic microenvironment modulated chemoresistance through ferroptosis. All in all, the 3D printed model may serve as a new platform for illustrating the underlying mechanism of the TME induced chemoresistance, and also proposed a novel therapeutic strategy for PDAC through NRF2 inhibition, which effectively promotes ferroptosis to overcome chemoresistance.